Tar sand retorting

ABSTRACT

The particular embodiment described herein as illustrative of one form of the invention utilizes a system for retorting bituminous sands which includes a horizontal bed of such materials moving first through a retorting zone, and then a burning zone. Vertical openings are formed in the bed to provide for the flow of gases through the bed in the retorting operation. Heat exchangers utilize the heat of educted hydrocarbons and burning coke to supply heated gas to the retorting system.

United States Patent Inventor John D. Bennett [56] Reierences CitedRichardson, UNITED STATES PATENTS 2.5 gif'fi 3,009,863 ll/l96l Angevine201/6 x t d N 1971 3,258,409 6/1966 Schenck m1 201/6 lig t 3,487,00212/1969 Chaney et al. 208/11 Philadelphia, Pa. 3,509,027 4/1970 Savageet al. 20l/29 Primary Examiner-Curtis R. Davis Attorneys-George L.Church. Donald R. Johnson, Wilmer E. TAR SAND RETORTING McCorquodale,Jr. and John E. Holder 8 Claims, 3 Drawing Figs.

U.S.Cl 208/11, ABSTRACT The 1 particular embodiment descnbed hereln as ICl 201/6 20l/32' 201/40 202/ 3 illustrative of one form of the inventionutilizes a system for nt. ..Cl0bg53/ 06, retoning bimminous Sands whichincludes a horizontal bed of M Sc h g 208 l 8' such materials movingfirst through a retorting zone, and then m u a burning zone. Verticalopenings are formed in the bed to I provide for the flow of gasesthrough the bed in the retorting operation. Heat exchangers utilize theheat of educted hydrocarbons and burning coke to supply heated gas tothe retorting system.

PATENTEU uuvso l97| INVENTOR JOHN D. BENNETT ATTORNEY TAR SAND RETORTINGBACKGROUND OF THE SYSTEM This invention relates to the recovery of oilfrom bituminous sands, and more particularly, relates to an improvedprocess and apparatus for the more effective recovery of valuablehydrocarbon products from oil-bearing minerals, such as tar sands.

The material treated according to the method of the present invention isobtained from natural deposits existing in various parts of the world.Typical of such deposits are those found in the Province of AlbertaCanada particularly in the vicinity of the Athabasca River. These tarsands, in their naturally existing states, are heavily saturated with aviscous oil, and may be mined or removed from their naturally existingstate by conventional mining methods. The tar sands with which we areconcerned here are to be distinguished from the highly carbonaceoussolid shale materials, which on thermal treating yield hydrocarbonproduct.

In the following description, the phrases bituminous sand" or tar sand"are used to refer generally to all granular solid bituminous orpetroliferous materials soaked with a usually highly viscous liquid orsemiliquid hydrocarbonaceous material, although it specifically refersto a characteristic type of bituminous solid consisting of discreteparticles of sand bound together by a continuous viscous hydrocarbon oilphase. This terminology is used for the sake of simplicity ofdescription, and it should be understood that the process and apparatusherein described may be applied to other solids similarly containing abituminous or viscous hydrocarbonaceous coating.

Tar sands are composed of a siliceous material, generally having a sizegreater than that passing a 325 mesh screen, saturated with a relativelyheavy, viscous bitumen in quantities of from 5 to 21 weight percent ofthe total composition. More typically. the bitumen content of the sandsis about 8 to percent. This bitumen is quite viscous and containstypically 4.5 percent sulfur and 38 percent aromatics. Its specificgravity at 60 F. ranges typically from about 1 to about 1.06. The tarsands also contain clay and silt from I to 50 weight percent of thetotal composition. Silt is normally defined as mineral which will pass a325 mesh screen, but which is larger than 2 microns. Clay is mineralsmaller than 2 microns, including some siliceous material of that size.

There have been two well-known methods in use for the separation ofcrude oil from bituminous sands. One is what is known as the hot waterseparation method," and the other is the so-called cold water method.

In the hot water method, the bituminous sands are jetted with steam andmulled with a minor amount of hot water at temperatures in the range of140 to 2 10 F. The resulting pulp is dropped into a stream ofcirculating hot water, and carried to a separation cell, sand settles tothe bottom as tailings, and bitumen rises to the top in the form of anoil froth. An aqueous middlings layer containing some mineral and somebitumen is formed between these layers. A scavenger step may beconducted on the middlings layer from the primary separation step torecover additional amounts of bitumen This latter step usually comprisesaerating the middlings to form a froth. These froths may be combined,diluted with naptha, and centrifuged to remove more water and residualmineral. The naptha is then distilled off, and the bitumen is coked to ahighquality crude suitable for further processing.

According to the cold water method, a diluent such as kerosene is addedto the bituminous sand as it enters the plant. The mixture of sand anddiluent is passed through a mill where the lumps are broken down and thekerosene thoroughly mixed with the bitumen The mixture is thenintroduced into a large volume of water, where most of the sand settlesout, and an oil froth or emulsion is floated off the top in a mannersimilar to the hot water method. The oil froth recovered by this methodis then put through a dehydrator, and is passed on to other steps ofrefining. Water, which is picked up in the froth, must be separated anddisposed of.

Numerous problems are associated with the above methods. In the hotwater process, fines in the water must be settled in order to dispose ofthe water. The settling process is time-consuming, and requires a greatamount of space and equipment. In addition, fines in the oil require acentrifuging step for their removal. The cold water process, on theother hand, requires settling steps which are time-consuming, and inaddition, water separation processes which are expensive. In addition,large amounts of solvent are used in the process which are noteconomically recoverable.

On the other hand, retorting methods which in the past have been appliedto shale oils provide the additional advantage of partially coking thehydrocarbon during the separation process, to eliminate the disposalproblem associated with the water separation process, and in particular,the disposal problem involved in settling the fines in the hot waterprocess.

Prior art disclosures offer numerous processes primarily intended forretorting oil-bearing shales, but often described as being equallyapplicable to the retorting of tar sands. Examples are the followingU.S. patents pertaining to retorting of carbonaceous materials, such asoil shale, coal and tar sands in bed fonn: U.S. Pat. Nos. 2,406,810;2,885,338; and 3,130,!32. Disclosures which include tar sands among thecarbonaceous feed materials described generally fail to take intoaccount the marked difference in character of tar sands as compared tooil shales. The latter material is hard rock which is nonpliable, and abed composed of pieces of the oil shale rock has no tendency to collapseduring retorting. On the other hand, tar sands are plastic material, andpieces thereof nonnally are incapable of maintaining their shapes underretorting conditions.

In view of the distinctly different physical characteristics of oilshales on the one hand, and tar sands on the other, prior proceduressuitable for retorting oil shales have not proved to be applicable totar sands. These processes are unsatisfactory for tar sands due to thefact that the chunks or particles will not retain their shape duringheating, as a consequence of which the bed of material tends to collapseand the particles therein tend to fuse at the high temperature requiredfor retorting. As this occurs, the pressure drop necessary to maintain areasonable flow of hot gases through the bed rises inordinately. Inorder to drive out most of the oil from the mined sands, a relativelylarge volume of hot gas is required, usually in excess of 1 pound of hotgas per pound of bituminous sands, in order to heat the entire bed tothe desired retorting temperature. The temperature must be in excess of700 F., and desirably in the range of l,000 to 1,500 F. As the chunks orparticles of bituminous sands are heated toward such temperature levels,the particles soften and the weight of the bed causes it to collapse.With the bed in collapsed condition, the cost of compressing asufficient amount of gas to heat the entire mass to retortingtemperature becomes excessive, making such a retorting processuneconomical and impractical.

The present invention overcomes this problem resulting from collapsingof the tar sand bed during retorting and avoids the expense otherwiseentailed in compressing retorting gas. Practice of the invention permitsthe retorting operation to be carried out utilizing fans or blowers toeffect the necessary circulation of hot gas through the bed ofbituminous sands instead of compressors.

It is therefore an object of the present invention to provide a new andimproved method and apparatus for retorting tar sands.

SUMMARY OF THE INVENTION With these and other objects in view, thepresent invention contemplates a retort system for retorting bituminousmaterials which includes a horizontally moving bed of such materialswhich are compacted and then perforated prior to entry into the retort.Such perforating provides vertical flow channels through the compactedbed of material to permit a controlled distribution of heat and burningwithin the retorting apparatus. The retorting apparatus is comprised oftwo zones, the first being a retorting zone for educting volatilehydrocarbon materials from the horizontal bed. The second zone, intowhich the bed passes after eduction of hydrocarbons therefrom, comprisesa burning zone which burns the remaining coke within the materials. Heatfrom such burning operation is transferred to the retort zone forproviding retort heat. A heat exchanger also utilizes heat from theeducted hydrocarbons for heating the burning zone.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a perspective view of anapparatus for compacting a bed of bituminous materials and formingvertical holes therethrough;

FIG. 2 shows a horizontal compacted bed of such materials with holesformed therein; and

FIG. 3 shows a schematic representation of a retorting system carryingout the principles of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1 ofthe drawings, an apparatus is shown for forming vertical flow pathsthrough a bed of bituminous sand material to be retorted. Bituminousmaterials which are mined from the earth are placed on top of theconveyor 12. The conveyor has side members 14 which form a trough forholding the materials in place on the conveyor. The conveyor isconstructed in hinged sections to permit movement of the bottom and sidemembers over a pulley. The materials are moved on the conveyor untilthey are aligned with a compacting and perforating device 16 which ispositioned above the conveyor. The compacting and perforating device 16is comprised of a body platen 20 having downwardly extending perforatingmembers 18 which are formed in the shape of a truncated cone. Uponlowering the compacting and perforating device 16 onto the conveyor, thelower face of the platen 20 engages the materials on the conveyor andcompacts these materials into the conveyor trough formed by the conveyor12 and sidewalls 14. The platen is sized to be received on the conveyorbetween the sidewalls so that the top of the compacted material is belowthe top of the sidewall members 14 in the conveyor. The perforators 18are arranged to be aligned with openings 22 in the conveyor. During theperforating operation the platen is lowered onto the material beingcarried by the conveyor. The material is thus compacted between theplaten and the conveyor trough. The perforators form holes or conicallyshaped openings through the compacted material to provide communicationbetween the top and bottom sides of the compacted bed of materials onthe conveyor. It is to be understood that means (not shown) are providedfor coordinating the movement of the conveyor and platen so that theperforating members 18 will be alignable with the holes 22 upon movementof the compacter into the bed of materials.

The shape of the perforating members causes the tar sands to belaterally displaced and thereby compacted upon entry of the conicallyshaped members into the material. Compacting of the material about theopening provides a strong structure which will retain its shape andthereby maintain an opening while the material is being moved throughthe retorting process.

FIG. 2 shows a cutaway view of a portion of such material as it appearsafter the compacting and perforating operation. The bed of materials 24has conically shaped openings 26 formed therein with the large portionof the cone at the top of the bed and the small portion of the truncatedcone at the bottom of the bed. The openings are spaced in the bed toprovide an approximately equal thickness of material in all directionsfor purposes to be hereinafter described. The thickness of the bed, andsize and spacing of the openings therein will be determined by the rateof movement of the bituminous materials through the retorting system.

The compacted material forming the bed together with the conicalperforations therein create a bed of material which is characterized bya substantially greater strength than the unconsolidated materials whichare originally placed on the conveyor belt. The conical openings providea strong unsupported sidewall portion which is designed to maintain itsform throughout the retorting operation, while being subjected tomovement of the conveyor and movement of gaseous fluids therethroughduring the retorting and burning operations to be described hereinafter.Such openings provide a means for passing gaseous fluids through thebeds and at the same time expose a maximum amount of cross-sectionalarea of the bed to such gases, leaving an equal volume of such materialsunexposed between the opening to effect a uniform exposure of suchmaterials to the atmosphere within the retorting zones. By maintaining aproper feed of materials through the retorting system, such materialsare uniformly treated and therefore a maximum amount of hydrocarbons maybe educted therefrom together with a maximum amount of thermal energywhich is derived from the materials during passage through the burningzone.

Referring now to FIG. 3 of the drawings, a conveyor 30 is shown formoving a continuous bed or bricquet 24 of bituminous materials into aretorting apparatus. While the conveyor 30 is shown passing over pulleysat the ends of the retorting mechanism, additional pulleys (not shown)are provided for diverting the conveyor outwardly around the retortingmechanism to produce a continuous conveying system. The apparatusincludes a first retorting zone 32, provided with a housing 34 enclosingthe zone. Insulating materials such as at 33 are used throughout theconstruction of the retort system to maximize the utilization of heatenergy generated in the system. A swinging door seal 36, rides lightlyalong the top surface of the bed of material to provide a sealedenclosure to the interior of the retort zone. The door seal is sized toswing downwardly between the sidewall members 14 on the conveyor. A pipe70 communicates with the top of the housing 34. Hot gases are forcedthrough pipe 70 into the retort zone to bring the zone 32 to anapproximate temperature range of from l,000 to l,300 F. Such heatedgases move about and through the bed of materials to raise thetemperature of such materials to a retorting temperature ofapproximately 750 900 F. Such heated gases pass through the openings 26in the material and openings 22in the conveyor into a funnel-shapedenclosure 38 positioned below the conveyor beneath the retort zone.Enclosure 38 has an opening 39 in its sidewall to pennit passage of suchhot gases from the enclosure. The enclosure 38 also provides a means forcatching educted hydrocarbons which are driven from the bed of materialduring heating in the retort zone. A cover 41 prevents eductedhydrocarbons from entering the opening 39. The funnelshaped housingtenninates in an outlet conduit 40 at the lower end thereof. The conduit40 provides means for moving the educted hydrocarbon fluids into a heatexchanger 42. The heat exchanger 42 may be of any well-known type whereheat is conducted through tubular members from one medium to another. Inthis case the heat exchanger provides a means for transferring heatenergy in the educted hydrocarbons to a gas, such as fresh air, beingblown through conduit 44 by means of blower 46. The hydrocarbonmaterials are thus cooled and leave the heat exchanger through theconduit 48. The educted hydrocarbons enter the exchanger from conduit 40at approximately from 200 600 F. Air entering the heat exchanger throughconduit 44 will absorb some of this heat energy, before exiting the heatexchanger through conduit 72 for purposes to be hereinafter described.

The moving bed of bituminous materials leaves the retort zone 32 andmoves through a swinging door seal 50 into a second, burning zone 52.Heated air is supplied to the burning zone 52 by means of a pipe 54,which communicates with the top of the burning zone. A defuser 53 ispositioned below the opening of pipe 54 into the burning zone. Thedefuser provides a means for regulating the distribution of hot gaseswithin the burning zone. The heated air entering the burning zone causesthe fixed" carbon or coke within the sand to be burned. The coke servesas a bonding material to hold the sand in its compacted and perforatedshape. As the coke burns, the face of the exposed material becomesunconsolidated to the extent that the burned face slufi's off and dropsby gravity through the openings in the conveyor. The openings in thematerial are thereby enlarged as the burning takes place until thematerial has substantially completely burned. The velocity andturbulence of hot gas moving through the openings 26 in the materialwill carry the material out the openings 22in the conveyor. Means (notshown) may be provided at the end of the conveyor for sweeping anyremaining sand from the conveyor before the conveyor exits the retort.

A heat exchange chamber 56 is formed below the conveyor belt, beneaththe burning zone. The heat exchange chamber is provided with baffles 57which form vertical channels 58 interconnecting the upper and lowerportions of the chamber. The channels 58 provide a means for theunconsolidated sand to fall to the bottom of the chamber, where theycollect on a conveyor belt 60 for removing spent sand to the exterior ofthe retort system. Upper and lower transverse flow ducts 62, 64respectively, are formed within the baffles 57 positioned within theheat exchange chamber. The flow ducts establish a means for transferringheat energy from the burned sand to gases passing within the ducts 62and 64. Additional baffles or surface area may be provided in thechamber 56 to facilitate such heat exchange. The upper duct 62 isconnected at its left end, as viewed in FIG. 3, with the opening 39 inthe funnelshaped enclosure 38 beneath the retort zone. The opposite endof the duct 62 is connected by means of a conduit 66 with a blower 68for moving gaseous fluids between the duct 62 and the pipe 70communicating with the top of the retort zone 32. The flow path justdescribed creates a continuous circulation of gases within the retortzone. The movement of such gases through duct 62 adds heat energy to thegases, and thereby maintains the temperature within the retort zone at alevel which will insure retorting of the volatile constituents from thebituminous material. Such temperature may, for example, be in the rangeof 1,000 1,300" F. In the event that fogging occurs in the enclosure 38,a defogging device may be placed in the entry to duct 62 to prevent thefog from getting into the heat exchanger and forming coke depositstherein.

The lower transverse duct 64 within the heat exchange chambercommunicates at its left end with a conduit 72 leading from the heatexchange device 42. The lower duct provides a means for passing gaseousfluids which emit from the heat exchanger 42 through the heat exchangechamber 56 for supplying additional heat energy to such gaseous fluids.The lower duct 64 connects at its other end with conduit 74, which inturn communicates with conduit 54 and the upper end of the burning zonewithin the retort system. Gases entering the burning zone throughconduit 54 may have an approximate temperature range of from 500 l,000F. Such heated gas flowing into the burning zone maintains the burningzone at a temperature which will insure burning of the coke or fixedcarbon residue within the bituminous materials. The burning of such cokeor fixed carbon materials provides additional heat to gaseous fluid flowthrough the heat exchange chamber to maintain temperatures within theretorting system. The burning coke may raise the temperature in theburning zone to an approximate range of from 1,300- l,700 F.

The hot gases which are moved into the upper end of the burning zone bymeans of the blower 46, pass downwardly through the burning sands, theconveyor, and outwardly through the vertical flow paths 58 within thechamber 56. Such gases then continue along the path taken by the spentmaterial conveyor belt into a plenum 77 at the end of such conveyor,where they are permitted to escape through a flue gas chimney 78.Additional blowers other than those shown may be provided throughout thesystem to provide for necessary heat transfer. It is anticipated that asubstantial amount of the heat energy will have been removed from suchescaping gases so that the temperature of the gas escaping throughchimney 78 will be very low and contain relatively few unburnedhydrocarbon elements. A transversely moving conveyor 80 at the bottom ofthe plenum 77 receives sand from conveyor 60 for removal to a disposalsite.

Summarizing the operation just described, mined bituminous tar sandmaterials are loaded on a conveyor 30 where they are compacted andperforated by means of an apparatus as shown in FIG. 1 for performingthis operation. Such perforated and compacted material is then movedinto a first sealed retort zone 32 where heated gases are passeddownwardly through openings 26 within the material to heat the materialand permit the flow of volatile hydrocarbon fluid therefrom into thefunnel-shaped enclosure 38 below the retort zone. Next, the retortedbituminous materials are passed into a burning zone 52 where theremaining fixed carbon or coke therein is burned. While such coke isburning, a gaseous fluid is passed through the burning zone to move theheat energy evolving therefrom into a heat exchange chamber 56 below theconveyor 30. A pair of transverse heat exchange ducts 62, 64 within thechamber 56 move gaseous fluids through the chamber to remove the heatenergy from the burning zone gas for: 1) Heating the circulating fluidthrough the retort zone; and (2) Supplying additional heat to the bumingzone. As the coke is burned from the bituminous material in zone 52, thesands containing such coke become unconsolidated and are permitted todrop through the openings 22 within the conveyor belt and verticalchannels 58 within the chamber 56 onto a spent material conveyor belt60, which removes such unconsolidated sands from the retort zone to thedisposal conveyor 80.

It is pointed out that while approximate temperature operating rangeshave been described in conjunction with this retort system, suchoperating conditions are not intended to be limiting. Retort operatingconditions would, of course, be dependent on factors peculiar to eachsystem and the physical properties of the material to be retorted. inaddition, while the overall system has been described with respect to abelt-type conveyor, it is readily seen that other conveying system, forexample, a circular hearth-type system, might be employed to move thematerials in a retort.

Therefore, while particular embodiments of the present invention havebeen shown and described, it is apparent that changes and modificationsmay be made without departing from this invention in its broaderaspects, and therefore, the aim in the appended claims is to cover allsuch changes and modifications as fall within the true spirit and scopeof the invention.

What is claimed is:

l. A method of retorting bituminous tar sands materials comprising thesteps of: compacting a bed of bituminous materials; forming flowchannels in such bed of materials; moving the materials on a horizontalconveyor through a retorting apparatus, such conveyor having passages inalignment with the flow channels; passing a treating fluid through suchflow channels to educt volatile hydrocarbons from the materials; passingthe educted hydrocarbons out of the retort apparatus through thepassages; moving the bed of materials into a burning apparatus; furtherheating the materials to burn remaining hydrocarbon constituents in thematerials until the materials are unconsolidated; and passing theunconsolidated materials out of the burning apparatus through thepassages.

2. The method of claim 1 wherein the flow channels are formed byproducing vertical holes through such bed of materials.

3. The method of claim 2 wherein said holes are in the shape of atruncated cone.

4. The method of claim 1 wherein said bed is horizontally disposed.

5. A method of retorting bituminous sand material comprising the stepsof: moving a horizontal bed of such material into a retort zone on aconveyor, such conveyor having vertical passages therein; passing heatedfluid through vertical holes formed in the bed of material tosubstantially remove all the hydrocarbons from the material, leavingcoke in the material; moving the coke containing material into a burningzone; passing fluid through the vertical holes in the material while thecoke in such material is burned to heat the retorting fluid; and passingcoked material of the burning zone through the vertical holes andthrough the conveyor passages to continuously expose fresh coke to theburning zone.

6. The method of claim wherein the bituminous sand materials, prior topassing through the retorting zone, are compacted into a substantiallyimpermeable bed which is then perforated to form vertical holes throughthe bed.

7. A method for retorting tar sand comprised of noncarbonaceousmaterials bonded together by volatile hydrocarbon and fixed carbonconstituents comprising the steps of: horizontally moving a bed of suchmaterials on a conveyor into a retort having first and second zones, thebed of materials and conveyor having openings therein; moving hot fluidsthrough such openings to heat the bed of materials in the first zone toa temperature sufficient to educt the volatile zone for burning theresidue of said first zone; first fluid transfer means for passing afluid into said second zone; first heat exchanger means for transferringheat from said educted hydrocarbons to said fluid passing into saidsecond zone; second fluid transfer means for passing a fluid into saidfirst zone; and second heat exchanger means for transferring heat fromsaid burned residue to said fluid passing into said first zone.

* I. I I l

2. The method of claim 1 wherein the flow channels are formed byproducing vertical holes through such bed of materials.
 3. The method ofclaim 2 wherein said holes are in the shape of a truncated cone.
 4. Themethod of claim 1 wherein said bed is horizontally disposed.
 5. A methodof retorting bituminous sand material comprising the steps of: moving ahorizontal bed of such material into a retort zone on a conveyor, suchconveyor having vertical passages therein; passing heated fluid throughvertical holes formed in the bed of material to substantially remove allthe hydrocarbons from the material, leaving coke in the material; movingthe coke containing material into a burning zone; passing fluid throughthe vertical holes in the material while the coke in such material isburned to heat the retorting fluid; and passing coked material of theburning zone through the vertical holes and through the conveyorpassages to continuously expose fresh coke to the burning zone.
 6. Themethod of claim 5 wherein the bituminous sand materials, prior topassing through the retorting zone, are compacted into a substantiallyimpermeable bed which is then perforated to form vertical holes throughthe bed.
 7. A method for retorting tar sand comprised of noncarbonaceousmaterials bonded together by volatile hydrocarbon and fixed carbonconstituents comprising the steps of: horizontally moving a bed of suchmaterials on a conveyor into a retort having first and second zones, thebed of materials and conveyor having openings therein; moving hot fluidsthrough such openings to heat the bed of materials in the first zone toa temperature sufficient to educt the volatile hydrocarbon constituentstherefrom; and thereafter moving hotter fluids through such openings toheat the bed of materials in a second zone to a temperature sufficientto burn the fixed carbon constituents in said materials so that theremaining noncarbonaceous materials become unconsolidated and fallthrough the openings in the conveyor.
 8. In an apparatus for retortingbituminous sands: means for moving a horizontal bed of such materialsthrough the retorting apParatus, said apparatus including a first zonefor educting volatile hydrocarbons from such material and a second zonefor burning the residue of said first zone; first fluid transfer meansfor passing a fluid into said second zone; first heat exchanger meansfor transferring heat from said educted hydrocarbons to said fluidpassing into said second zone; second fluid transfer means for passing afluid into said first zone; and second heat exchanger means fortransferring heat from said burned residue to said fluid passing intosaid first zone.